An element B of a given class of Boolean algebras is universal if every other element of the class is isomorphic to a subalgebra of B. In the context of Banach spaces, we have similar notions considering isomorphisms or isometries of Banach spaces. We will discuss the existence of universal objects for some classes of Boolean algebras and of Banach spaces and their interaction. We are particularly interested in the classes of all objects of a fixed size - cardinality of Boolean algebras and density character of Banach spaces - and we shall compare the countable/separable and the uncountable/nonseparable settings.

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